A launcher needs to:
1) Read the registry for ONLY the fs2 reg entries, including video card, sound and network.
2) Allow ONLY changing between supported video types, which means probably some kind of drop down that changes the registry entry from
"Direct 3D - Primary Display Driver (1024x768)"
"OpenGL - Primary Display Driver (1024x768)"
Or 640x480, for instance
3) SET registry entries for typical, default values (unless you are going to write a detect routine that can autodetect d3d/opengl) and write those entries to the registry if they don't exist, for ALL required components (thus obviating the need to run the fs2 launcher first).